Present methods of isolating contaminated sites by making barriers (such as concrete retaining walls and plastic lined structures) do not have the durability or effectiveness of vitrified soil. Furthermore, present methods may require removal of soil and waste materials, as well as handling steps which are expensive and involve the possibility of hazardous exposure during processing.
Solidification of soil by in-situ melting and vitrification using heat generated in the soil itself between spaced electrodes has previously been accomplished as disclosed in Brouns et al. U.S. Pat. No. 4,376,598 issued Mar. 15, 1983 and further defined and clarified in Brouns et al. Reexamination Certificate 1142nd issued Oct. 17, 1989. Although Brouns et. al. suggest that the method of 1142nd may be used to cover or encapsulate waste materials buried in soil, only limited encapsulation is possible. Using the method of Brouns et al. the volume of soil to be vitrified must be sufficiently near the soil surface that it may be engulfed by a melt initiated at the soil surface and propagated downward by melting. Another limitation of Brouns et al. is that the shape of the melted soil is passively determined by the physical characteristics of the soil which results in melts having large cross sectional areas.
This invention combines the advantages of barriers with the advantages of vitrified soil, the ability to isolate a site on any or all sides with a material that is durable and impermeable.
Although isolation of an underground contaminated site is envisioned as a primary use of this invention, other uses include but are not limited to, ground movement monitoring, in-situ load bearing structures for buildings and towers, and control of water table elevation are envisioned.